Atherosclerosis is a leading cause of death in western societies despite many attempts to prevent and cure this disease. Therefore gene therapy treatment could be for atherosclerosis treatment. Human APOA-I and the mutant hu APOA-IMilano have a protective effect in mice and humans respectively. Therefore the goal of this proposal will be to protect and cure highly atherosclerosis susceptible LDLR-negative mice from atherosclerosis by using these genes as therapeutical agents in gene therapy treatment. In breeding experiments and competitive bone marrow transplantation experiments using hu APOA-I transgenic bone marrow, the protective effect of hu APOA-I and the minimum concentration of plasma APOA-I necessary to achieve protection from atherosclerosis will be determined. Concentrations of serum APOA-I in the recipients and development of atherosclerotic lesions will be examined. I will then be determining if protective APOA-I levels can be achieved by gene therapy treatment using retroviral constructs including hu APOA-I or hu APOA-IMilano driven by various promoters. Several culture conditions and transduction strategies will be evaluated to achieve high transduction efficiencies of bone marrow. Competitive bone marrow transplantation will be performed to determine the minimum amount of retroviral vector transduced hematopoietic cells necessary to protect or cure from atherosclerosis. Development of gene therapy methods in mice will provide scientists with tools to develop therapy techniques applicable in humans.